Direct access to the vascular system is a quick and effective way to administer a variety of drug therapies, provide nutrition, and/or sample blood. Currently, regular access to the vascular system is gained by using a device specifically designed for this task. Several types or families of these devices exist in the market today. Among them are needles, catheters and a group of devices known as implanted access portals.
Vascular access has evolved through the years to improve treatment of a number of chronic and non-chronic diseases. Needles have been used for many years to inject vaccines and antibiotics or withdraw blood. Although still widely used today, needles have several limitations that do not allow them to be used with all therapies. In the early 1970's the use of vascular access catheters was perfected. Vascular access catheters allowed long term antibiotic, chemo, and nutritional therapies to be administered without having to change the access device. Additionally, vascular access catheters made it possible to introduce a medicament into a large enough vessel to allow the hemo-dilution required for some of the more toxic therapeutic drugs. This type of catheter provides a significant improvement over needles for long-term access, however, the external segment of such catheters may be prone to infection and requires constant maintenance. The latest development in vascular access is the implanted access portal, or ports. These portals eliminate the need for an external segment and therefore do not have the drawbacks of catheters.
Although considered new technology in the field of vascular access, implanted access portals have existed in the market for over 20 years. Use of these products has increased dramatically during this period because they are generally the device of choice for long-term vascular access. They are particularly suited for long-term use because the entire device is implanted under the skin. Implantability is one factor in the success of the implantable access portals because it allows the patient to perform ordinary daily tasks such as bathing and swimming without worrying about harming an external segment of an access device or increasing the chance of infection. Thus the quality of life for the patient is improved and the clinician is presented with fewer device related complications.
Typically implanted access portals consist of a housing, a self-sealing septum, and an attachable or pre-connected catheter. Portal housings can be made of a variety of materials including plastic, metal, or a combination of both. The self-sealing septum is generally made of an elastomer such as silicone. Catheters are also generally made of a highly flexible material such as silicone or polyurethane. Different materials are used to manufacture the components to achieve certain desired characteristics in the portal (i.e. plastic is not radiopaque, therefore the port will not show up on fluoroscopy).
Implanted access portals are also designed in such a way that their size (height and footprint), shape, and number of lumens are appropriate for the intended use. Number of lumens can be critical if a patient requires simultaneous infusion of incompatible solutions or isolation of blood sampling. As concurrent therapies become more popular the need for a wider variety of dual-lumen ports has increased.
During the life cycle of an implanted infusion portal a variety of complications can arise that may limit its functionality or render it useless altogether. Among these complications is “sludge buildup” or unwanted buildup of precipitate in the portal reservoir. This buildup is generally caused by improper or inadequate flushing of the portal. Typically portals are cleared or flushed immediately after aspiration or infusion. Routine flushing or maintenance is also performed when a portal is used infrequently or not at all. Flushing usually consists of injecting saline solution or saline solution containing an anti-coagulant, such as Heparin, through the reservoir and out the catheter into the vascular system. Generally the instructions for use will specify the volume of fluid and frequency required for proper maintenance.